Methods and Devices for Reducing NOx Emissions Produced by Diesel Engines

ABSTRACT

The invention includes methods and devices for preventing excessive NOx formation during the combustion event of a compression-ignition engine with any combustible fuel (diesel, Jet-A, JP8, bio fuel, etc).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/520,660, filed Nov. 6, 2021, now U.S. Patent No. ______, which is acontinuation of U.S. patent application Ser. No. 16/254,285, filed Jan.22, 2019, now U.S. Pat. No. 11,193,454, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/620,569, filed Jan. 23, 2018,each of which is hereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC OR ASA TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM (EFS-WEB)

Not applicable.

STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINTINVENTOR

The inventor has not made any prior public disclosure of the inventionsdisclosed herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The inventions described herein generally relate to methods and devicesfor reducing NOx emissions produced by diesel engines.

2. Description of Related Art

Current market technology for reducing NOx emissions in diesel enginesfocuses on ways to reduce NOx in the tailpipe of the engine's exhaustgas system. The use of this technology is causing sub-standarddurability and lifetime issues with the engine and exhaust gas systems.Exhaust gas recirculation (EGR), for example, is a common method of NOxabatement, but the use of EGR increases CO2, HC, and CO emissions in theengine exhaust. EGR also reduces engine life due to the engine'sre-ingestion of exhaust gas, which is full of soot, as soot is abrasiveand leads to internal engine wear of rockers arms, bearings, etc.Additionally, EGR only reduces NOx about 50%, which is not enough tomeet emission regulation requirements. As such, after-treatment in theexhaust system is also required to further reduce the NOx emissions.

Illustrative such after-treatment techniques include selective catalyticreduction (SCR), which injects urea, which is also known as dieselexhaust fluid (DEF) into the exhaust gas. The urea or DEF reacts withthe NOx in the exhaust to break it down chemically into harmless gases,in order to meet EPA requirements.

The devices described above have many field issues/malfunctions leadingto high warranty costs. At the manufacturing level, for example, thehardware to implement the above-discussed systems can add $2000 to thevehicle cost when built.

Rather than addressing NOx in the exhaust gas, NOx can instead beaddressed during the combustion event, so as to alleviate the need forcomplex exhaust systems and allow for a much cleaner burning engine.

For example, some have studied the injection of water into the airintake ports of diesel engines during the combustion cycle, while othershave studied the intermittent injection of fuel and water through thesame injector during the combustion cycle. These approaches, and others,are more thoroughly discussed in the following references, each of whichis incorporated herein by reference in its entirety: U.S. Pat. No.4,502,420 to Mezger, U.S. Pat. No. 4,558,665 to Sandberg et al., U.S.Pat. No. 5,148,776 to Connor, U.S. Pat. No. 5,522,349 to Yoshihara etal., and U.S. Pat. No. 7,216,607 to Mezheritsky et al. Although somethese techniques have served to reduce the presence of NOx in theexhaust gas, none of them have served to reduce NOx to a commerciallyviable level.

In view of the background in this area, there remain needs for improvedand/or alternative methods and devices for reducing NOx emissionsproduced by diesel engines. The present inventions are addressed tothose needs.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the invention provides a diesel engine that includes acombustion chamber. The combustion chamber has a volume that is definedby an inner wall of a cylinder liner, a top surface of a piston, and abottom surface of a cylinder head. A first injector is disposed withinthe cylinder head and has a first injector tip that extends to a firstlocation within the of the volume of the combustion chamber. A secondinjector is disposed within the cylinder head and includes a secondinjector tip that extends to a second location within the volume of thecombustion chamber. The first injector is configured to introduce a fuelinto the volume of the combustion chamber, and the second injector isconfigured to introduce an additional substance into the volume of thecombustion chamber. The introduction of the additional substance intothe volume of the combustion chamber reduces NOx formation within thevolume of the combustion chamber.

In another aspect, the invention includes an engine having a pluralityof combustion chambers, each of which has a volume that is that isdefined by an inner wall of a cylinder liner, a top surface of a piston,and a bottom surface of a cylinder head. Each of the volumes includes afirst injector tip that extends to a first location within the volume ofthe combustion chamber and a second injector tip that extends to asecond location within the volume of the combustion chamber. The firstinjector tip includes a plurality of apertures for introduction of afuel into the volume of the combustion chamber and the second injectortip includes a plurality of apertures for introduction of an additionalsubstance into the volume of the combustion chamber. The introduction ofthe additional substance into the volume of the combustion chamberreduces the overall combustion flame front temperature such that NOxformation is reduced during the combustion process.

In yet another aspect, the invention provides a method for reducing NOxformation in a diesel engine. The method includes the provision of adiesel engine having at least one combustion chamber, where the at leastone combustion chamber further includes a volume that is defined by aninner wall of a cylinder liner, a top surface of a piston, and a bottomsurface of a cylinder head. The method also includes the provision of afirst injector in communication with the volume of the at least onecombustion chamber for the introduction of fuel into the volume of theat least one combustion chamber, as well as the provision of a secondinjector in communication with the volume of the at least one combustionchamber for the introduction of an additional substance into the volumeof the at least one combustion chamber, whereas the introduction of theadditional substance into the volume of the combustion chamber reducesNOx formation.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 depicts a cross-sectional elevation view of an illustrativeembodiment of the invention.

FIG. 2A depicts a cross-sectional elevation view of an illustrativepiston of the invention.

FIG. 2B depicts a top view of the illustrative piston depicted in FIG.2A.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to certain embodiments thereof andspecific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations, further modificationsand further applications of the principles of the invention as describedherein being contemplated as would normally occur to one skilled in theart to which the invention relates.

FIG. 1 depicts a cross-sectional elevation view of an illustrativecombustion chamber 6 of the invention. As shown, the combustion chamber6 can include a volume V that is defined by the inner wall 1A of acylinder liner 1, the top surface 2A of a piston 2, and the bottomsurface 3A of a cylinder head 3 that is located above the cylinder liner1. The volume V of the combustion chamber can be varied by movement ofthe piston 2 within the cylinder liner 1 between a first piston positionFPP (depicted in FIG. 1 ) that corresponds to the position of the pistonwhen its top surface 2A is furthest away from the bottom surface 3A ofthe cylinder head and a second piston position SPP (not depicted in FIG.1 ) that corresponds to the position of the piston when its top surface2A is closest to the bottom surface 3A of the cylinder head. A series ofvalves (not depicted) can reside within the cylinder head 3 in order topermit the flow of air (and exhaust gas recirculation) into the volume Vof the combustion chamber 6, as well as the flow of exhaust gas out ofthe volume V of the combustion chamber 6. The valves (not depicted) canmove between open and closed positions, as necessary, to facilitate theflow of air and exhaust gas in and out of the volume V of the combustionchamber 6.

A first injector 4 can be disposed within the cylinder head 3 such thatits tip 4A extends to a first location FL within the volume V of thecombustion chamber 6 at a location that is disposed above the centerpoint CP of the area that defines the top surface 2A of the piston 2.The first injector 4 can be used to introduce a fuel F, such as a dieselfuel, into the volume V of the combustion chamber 6 during operation ofthe engine. As also shown in FIG. 1 , a second injector 5 can bedisposed within the cylinder head 3 such that its tip 6A extends to asecond location SL within the volume V of the combustion chamber 6.Given that the tip 4A of the first injector is disposed above the centerpoint CP, the tip 5A of the second injector 5 can be disposed at adifferent location within the volume V of the combustion chamber 6. Asshown, for example, the second injector 5 can be offset and at an angleso as not to interfere with the first injector 4 and its tip 4A. Theposition and angle of both the first injector 4 and its tip 4A, as wellas the second injector 5 and its tip 5A can be varied in the cylinderhead 3 to accommodate various cylinder head 3 designs.

In operation, a fuel F, such as a diesel fuel, can be introduced withinthe volume V of the combustion chamber 6 through the first injector 4and its tip 4A. An additional substance AS, such as water, can beinjected through the second injector 5 and its tip 5A. Such additionalsubstance AS can be introduced in such a manner so as to lower theoverall combustion flame front temperature such that NOx formation isreduced during the combustion process. In certain embodiments, it isdesirable to achieve an overall combustion flame front temperature ofabout 2100 K to about 2300K, including an overall combustion flame fronttemperature of about 2200 K.

In order to introduce the additional substance SA into the volume V ofthe combustion chamber 6 in a manner that appropriately reduces theoverall combustion flame front temperature, the first injector tip 4Aand the second injector tip 5A can be configured to provide desiredindividual spray patterns ISPF, ISPAS for the fuel F and the additionalsubstance AS. Such individual spray patterns ISPF, ISPAS, whenoverlapping, can provide an overall spray pattern OSP, as is depicted inFIG. 1 .

In addition to varying the individual and overall spray patterns ISPF,ISFAS, OSP, the manner and frequency of introduction of fuel F andadditional substance AS can be varied to reduce the overall combustionflame front temperature. For example, the first and second injectors 4,5 can each be configured to produce multiple introduction events percycle, with a cycle being the movement of the piston 2 from its firstpiston position FPP to its second piston position SPP (not depicted) andback to its first piston position (FPP). Such multiple introductionevents can be referred to as pre-introduction, main-introduction, andpost-introduction. Other multiple introduction events can also includesplit introduction, which generally includes two, medium-sized, spacedintroductions. Illustratively, each introduction event can include theintroduction of fuel F and/or additional substance AS into the volume Vof the combustion chamber 6. For introduction events that include thepartial or fully overlapping introduction of both a fuel F and anadditional substance AS into the volume V of the combustion chamber 6,such fuel F and additional substance AS may be introduced in differentquantities, at different pressures, and for different durations of time.In certain embodiments, it may be desirable to introduce a firstadditional substance AS into the volume V of the combustion chamber 6before combustion, a second additional substance during AS combustion,and a third additional substance AS after combustion. In otherembodiments, introduction events can include any suitable variation,including as little as one introduction event from each of the first andsecond injectors 4, 5, as well as numerous introduction events, such asthree, four, five or more introduction events from each of the first andsecond injectors 4, 5. Each introduction event can vary in duration, andvarious additional substances AS can be used for any introduction eventthrough the second injector 5 and its tip 5A.

Additionally, the number of introduction events, the amount of fuel Fand/or the amount of additional substance AS introduced during eachintroduction event, as well as the timing and duration of eachintroduction event can be configured based on the rpm and load of theengine. In some embodiments, for example, an additional substance AS,can be introduced through the tip 5A of the second injector 5 in asingle introduction event that comprises a burst, while in otherinstances, the additional substance AS can be introduced through the tip5A of the second injector 5 in multiple introduction events, each ofwhich comprises a burst of varying duration. Additionally, the durationof the introduction of an additional substance AS can vary with respectto the duration of the fuel F introduction event occurring in the firstinjector 4. Illustratively, introduction of the additional substance AScan occur before, during and/or after introduction of the fuel F, suchas in calibrated patterns. Additionally, introduction of the fuel Fthrough the tip 4A of the first injector 4 may also occur in a singleintroduction event comprising a burst, or alternatively in multipleintroduction events comprising bursts of varying durations, such as inconjunction with the introduction of additional substance AS through thetip 5A of the second injector 5. Moreover, the fuel F and the additionalsubstance AS can be introduced in any suitable pattern, which can bevaried, such as by varying the delivery pressure of the fuel F oradditional substance AS. Suitable introduction events are typicallycontrolled by an electronical control module (ECM).

The respective fuel F and additional substance AS pressures can besupplied by independent pumps and can be respectively controlled andvaried in pressure from 0 bar to 2000 bar or more as is suitable for theapplication. Each injection system pressure can be independent of theother, or alternatively can be the same. The injection pressure may varybased on rpm and engine load factor (0-100%).

In certain embodiments, the additional substance AS can include a gas orliquid. In embodiments where a liquid is used, it is typically desirableto atomize such liquid through the injector so that such liquid occupiesa substantially gaseous state in the combustion chamber. Suitable suchliquid additional substances can include any desirable liquid substance,such as water, windshield washer fluid, methanol, ethanol, or virtuallyany type of fuel. Gaseous additional substances, such as steam, LPG,CNG, etc., can also be introduced into the combustion chamber, andtypically do not need further atomization, although further atomizationmay be desirable in some embodiments.

As depicted in FIG. 1 , the top surface 2A of the piston 2 can include asubstantially flat topography. In other embodiments, however, thetopography of the top surface 2A of the piston can be varied, as is trueof the bottom surface 3A of the cylinder head 3. FIG. 2A, for example,which is a cross-sectional elevation view of an illustration piston 2 ofthe invention, depicts a piston 2 having a top surface 2A that includesa varied topography. As depicted, the top surface 2A can include acavity 2B that occupies the general shape of a bowl. The bottom of thecavity can include a high point HP that creates an annular recess AR inthe cavity 2B of the top surface 2A of the piston 2.

The topography of the cavity 2B can include any suitable configuration.Illustratively, for example, the topography of the cavity 2B can mirrorthe overall spray pattern OSP formed by respective individual spraypatterns for fuel ISPF and additional substance ISPAS such that thecavity 2B receives the overall spray pattern OSP when the piston 2 islocated at its second piston position SPP. Additionally, the high pointHP of the cavity 2B can be located at any suitable location, such asnear the center point CP of the area of the top surface 2A of the piston2. In other embodiments, however, the cavity 2B can include multiplehigh points HP, or can even include no high points, where the cavity 2Btakes on a more typical formation of a bowl. Additionally, the cavity 2Bcan also include any suitable depth, such as may be necessary to receiveany overall spray pattern OSP or a spray pattern for a fuel F or anadditional substance AS.

Turning now to FIG. 2B, a top view of the illustrative piston 2 depictedin FIG. 2A is shown. As shown, the top surface 2A of the piston 2includes the cavity 2B depicted in FIG. 2A. Also depicted in FIG. 2B isthe individual spray pattern for fuel ISPF and the individual spraypattern for additional substance ISPAS. The individual spray pattern forfuel ISPF includes 7 lobes 10 that emanate from the tip 4A of the firstinjector 4 which can be generally located above the center point CP ofthe top surface 2A of the piston 2. The individual spray pattern foradditional substance ISPAS also includes 7 lobes 15 that emanate fromthe tip 5A of the second injector 5. The fourteen lobes 10, 15 of therespective individual spray patterns ISPF, ISPAS combines to form theoverall spray pattern OSP.

The individual spray patterns ISPF, ISPAS and their locations can bevaried by changing how far each injector tip 4A, 5A extends below thecylinder head 3A and into the volume V of the combustion chamber 6, aswell as the topography of the top surface 2A within the cavity 2B of thepiston 2.

Additionally, such individual spray patterns ISPF, ISPAS canalternatively be varied by varying the type of injector, injector tip,and/or the introduction pressure.

The tip 4A of the first injector 4 depicted in FIG. 2B includes seven(7) apertures for introduction the fuel F into the volume V of thecombustion chamber 6. The tip 5A of the second injector 5 depicted inFIG. 2B likewise includes seven (7) apertures for introduction of theadditional substance AS into the volume V of the combustion chamber 6.

Each of the seven apertures creates the respective lobes 10, 15 depictedin FIG. 2B. In alternative embodiments, however, the first and secondinjector tips 4A, 5A can include any suitable number of apertures tointroduce the fuel F and additional substance AS into the volume V ofthe combustion chamber 6. Moreover, the angle of the spray coming out ofeach aperture can be varied to change the angle of the spray inrelationship to the top surface 2A of the piston 2. Each aperture in thefirst and second injector tips 4A, 5A has an aperture length, as well asan aperture diameter. There is a relationship between aperture lengthand aperture diameter that can be referred to as the L/D ratio. The L/Dratio can determine characteristics of the respective individual spraypatterns, ISPF, ISPAS, as well as the penetration of the spray and thedispersion of the spray within the volume V of the combustion chamber 6.As stated above, the characteristics of the respective individual spraypatterns ISPF, ISPAS can impact the overall spray pattern OSP. Incertain embodiments, for example, it is desirable to maximize theinteraction of the respective individual spray patterns ISPF, ISPASbecause this may slow the heat release of the burn and reduces peaktemperatures along the flame fronts.

In any embodiment of this invention, the features and controls can beintegrated with a computerized engine control module or as a stand-alonecontrol module that communicates with other modules in the application.Engine ECMS have internal logic to utilize sensor data and outputcontrol signals to various engine hardware to determine system function.

In other embodiments (not depicted), a single injector can be utilizedto inject two fluids independently of each other. General reference canbe made, for example to U.S. Pat. No. 8,459,575 to Ricco et al., whichis hereby incorporated herein by reference in its entirety, for adescription of a dual injector design that has two nozzles in oneinjector.

Alternative fuel injectors, such as a dual fuel injector with one nozzleand two check needles, can be used to implement embodiments of theinvention as are depicted in U.S. Pat. No. 8,733,326 to Kim et al.,which is hereby incorporated herein by reference in its entirety.

The addition of a second injector 5 (be it a second independentinjection or a single, dual tipped injector) can allow for increasedswirl inside the volume V of the combustion chamber 6 for better mixingdepending on the angle of attack for spray interference. Properimplementation will improve engine longevity due to less contaminantsformed during combustion.

The additional substance AS can provide desirable effects on the dieselburn rate and temperature to allow for reduced NOx, CO2 and PMemissions. HC and CO may increase, but these emissions can be cleaned upwith an oxidation catalyst in the exhaust system.

In certain embodiments, the invention can include any or all of thefollowing: a water supply tank, one or more pumps to supply theinjectors 4, 5 with proper pressure, by-pass loops if needed, a purgesystem, a priming system, a lubricating system, a pressure bleed system,fluid lines, common-rail, pressure monitoring, temperature sensing,fluid chemistry sensing, electronic control unit and software forcontrols.

This concept can be adapted to fit any suitable engine to achieve anydesired result (such as something other than NOx reduction) where thefollowing fuels can be injected through the first injector 4: diesel,bio-diesel fuel, Jet-A, JP8, gasoline, natural gas, and the like.Several types of fuel systems are on the market from pump stylemechanical injection pumps, to common rail or intensifier injectionsystems. These differences are inconsequential as it relates to adding asecond injection system for an additional substance AS.

Any suitable number of injectors, such as one, two, three, four, or fiveinjectors, can be used in embodiments of the invention, each of whichmay include single or dual injectors. By way of example, engines thatinclude larger combustion chamber 6 volumes V may need more injectors toachieve suitable combustion in accordance with embodiments of theinvention. In some embodiments, it may be desirable for the injectorsand/or their tips to atomize the fuel F or additional substance AS, butin other embodiments, full or partial atomization of the fuel F oradditional substance AS may not be desirable. The injectors may compriseany suitable material, such as carbon steel, stainless steel, and/or anysuitable plastic material, such as a polymer.

All publications cited herein are hereby incorporated by reference intheir entirety as if each had been individually incorporated byreference and fully set forth.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

1. A diesel engine, comprising: a combustion chamber, said combustionchamber including a volume that is defined by an inner wall of acylinder liner, a top surface of a piston, and a bottom surface of acylinder head; a first injector disposed within said cylinder head,wherein said first injector includes a first injector tip, wherein saidfirst injector tip extends to a first location within the of the volumeof the combustion chamber; a second injector disposed within saidcylinder head, wherein said second injector includes a second injectortip, wherein said second injector tip extends to a second locationwithin the volume of the combustion chamber; wherein said first injectoris configured to introduce a fuel into the volume of the combustionchamber; wherein said second injector is configured to introduce anadditional substance into the volume of the combustion chamber; whereinsaid introduction of said additional substance into said volume of saidcombustion chamber reduces an overall combustion flame front temperatureto from about 2100K to about 2300K such that NOx formation within saidvolume of said combustion chamber is reduced during the combustionprocess.
 2. The diesel engine of claim 1, wherein said fuel comprisesdiesel fuel.
 3. The diesel engine of claim 1, wherein said additionalsubstance comprises water.
 4. The diesel engine of claim 2, wherein saidfirst injector is configured to create an individual spray pattern forfuel within said volume of said combustion chamber.
 5. The diesel engineof claim 4, wherein said second injector is configured to create anindividual spray pattern for additional substance within said volume ofsaid combustion chamber.
 6. The diesel engine of claim 5, wherein saidtop surface of said piston further includes a cavity.
 7. The dieselengine of claim 6, wherein said cavity occupies the geometric shapeproduced by said individual spray pattern for fuel and said individualspray pattern for additional substance.
 8. The diesel engine of claim 1,wherein said overall combustion flame front temperature is about 2200K.9. An engine comprising: a plurality of combustion chambers, whereineach of said plurality of combustion chambers includes a volume that isdefined by an inner wall of a cylinder liner, a top surface of a piston,and a bottom surface of a cylinder head; wherein each of said volumesincludes a first injector tip that extends to a first location withinsaid volume of said combustion chamber and a second injector tip thatextends to a second location within said volume of said combustionchamber; wherein said first injector tip includes a plurality ofapertures for introduction of a fuel into said volume of said combustionchamber and wherein said second injector tip includes a plurality ofapertures for introduction of an additional substance into said volumeof said combustion chamber; wherein said additional substance isselected from the group consisting of windshield washer fluid, methanol,or ethanol; and wherein said introduction of said additional substanceinto said volume of said combustion chamber reduces an overallcombustion flame front temperature such that NOx formation is reducedduring the combustion process.
 10. The engine of claim 9, wherein saidfuel further comprises diesel fuel.
 11. The engine of claim 9, whereinsaid fuel further comprises biodiesel fuel.
 12. The engine of claim 9,wherein said first injector tip and said second injector tip aredisposed within a dual injector.
 13. The engine of claim 9, wherein saidoverall combustion flame front temperatures is about 2100K to about2300K.
 14. The engine of claim 13, wherein said overall combustion flamefront temperatures is about 2200K.
 15. A method for reducing NOxformation in a diesel engine, comprising: providing a diesel enginehaving at least one combustion chamber, said at least one combustionchamber further comprising a volume that is defined by an inner wall ofa cylinder liner, a top surface of a piston, and a bottom surface of acylinder head; providing a first injector in communication with saidvolume of said at least one combustion chamber for introduction of afuel into said volume of said at least one combustion chamber; providinga second injector in communication with said volume of said at least onecombustion chamber for introduction of an additional substance into saidvolume of said at least one combustion chamber, wherein said additionalsubstance is selected from the group consisting of windshield washerfluid, methanol, or ethanol, whereas the introduction of the additionalsubstance into said volume of said at least one combustion chamberreduces NOx formation.
 16. The method of claim 15, wherein each of saidat least one combustion chamber includes an overall flame fronttemperature that is from about 2100K to about 2300K.
 17. The method ofclaim 16, wherein said overall flame front temperature is about 2200K.18. The method of claim 16, wherein said first injector includes a firstinjector tip and said second injector includes a second injector tip.19. The method of claim 18, wherein said first injector tip and saidsecond injector tip are disposed within a dual injector.
 20. The methodof claim 15, wherein said top surface of said piston further includes acavity, said cavity having a bottom surface that includes a high pointso as to create an annular recess in said cavity of said top surface ofsaid piston.